Of course, the authors hope that you'll buy the book since most people prefer printed books to PDF and its more expensive to print it than to buy it. They're offering the complete book in PDF format as, essentially, advertising. This is apparently Ed Roman's idea. He did the same thing with the first edition of his book. I own that copy and found it to be a great book on EJBs. Since he's doing it again, he must have had a positive experience the first time around. Note: you will have to register with The Server Side to download the books.